Autohomeomorphisms of $\omega^*$: the quotient relation

Speaker:

Will Brian, University of North Carolina at Charlotte

Date and Time:

Friday, February 16, 2018 - 1:30pm to 3:00pm

Location:

Fields Institute, Room 210

Abstract:

Given two autohomeomorphisms f and g of N*, we say that f is a quotient of g when there is a continuous surjection Q from N* to N* such that Qg = fQ. In other words, f is a quotient of g if it is the ``continuous image'' of g, in the appropriate sense.

I have been investigating this relation, and will present some of the results of that investigation in my talk. For example, under CH: there are many universal autohomeomorphisms (an autohomeomorphism is universal if everything else is a quotient of it); the quotient relation has uncountable chains and antichains; there is an exact description of the quotients of a given trivial map. Under OCA+MA the picture is still murky: for example, there is a jointly universal pair of autohomeomorphisms (meaning everything else is a quotient of one or the other), but I do not know if there is a single universal automorphism. I will sketch some of these results and include several open questions.

Scheduled as part of

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